Technical Field
The present disclosure relates to an integrated electronic device for detecting ultraviolet radiation, and in particular for detecting the composition of ultraviolet radiation.
Description of the Related Art
As is known, numerous devices are available today that enable measurement of the amount of ultraviolet light to which a person is subjected during everyday life. Such devices commonly equip personal systems such as, for example, cellphones and wearable devices so that the latter are able to provide the user with indications regarding, precisely, the amount of ultraviolet light that reaches them. In particular, the devices for measuring the amount of ultraviolet light, referred to hereinafter as “ultraviolet detectors”, provide the user with indications regarding the degree of danger of the ultraviolet radiation to which they are subjected.
In detail, the spectral region of ultraviolet radiation is comprised between 100 nm and 400 nm. In addition, ultraviolet radiation is divided into:
UVA radiation, with wavelengths comprised in the 315-to-400-nm range;
UVB radiation, with wavelengths comprised in the 280-to-315-nm range; and
UVC radiation, with wavelengths comprised in the 100-to-280-nm range.
In nature, ultraviolet radiation is emitted by the Sun. In addition, UVC radiation is substantially absorbed by ozone in the atmosphere, before reaching the Earth; consequently, it is generally neglected when the effects of ultraviolet radiation on human beings are considered. UVA radiation and UVB radiation, instead, manage to pass through the atmosphere. In its passage through the atmosphere, UVB radiation is in any case attenuated more than UVA radiation, which, further, penetrates into the skin more effectively as compared to UVB radiation.
This having been said, typically ultraviolet detectors supply an index known as “UV index” (UVI), which is defined as:
            U      ⁢                          ⁢      V      ⁢                          ⁢      I        =                  K        er            ·                        ∫                      280            ⁢                                                  ⁢            n            ⁢                                                  ⁢            m                                400            ⁢                                                  ⁢            n            ⁢                                                  ⁢            m                          ⁢                                                            S                er                            ⁡                              (                λ                )                                      ·                          F              ⁡                              (                λ                )                                      ·                                                  ⁢            d                    ⁢                                          ⁢          λ                      ⁢        where Ker is a constant equal to 40 m2/W, Ser(λ) is the so-called “erythema reference action spectrum”, which is established by the International Lighting Commission (Commission Internationale de l'Éclairage—CIE), and F(λ) is the solar spectral irradiance, expressed in W/(m2·nm). As the UV index increases, the degree of danger of radiation increases.
The UV index provides a rough estimate of the danger of ultraviolet radiation. However, it does not enable precise knowledge of the spectral composition of ultraviolet radiation.